The research objective is to elucidate the control of coronary blood flow under normal and pathological conditions. The autonomic control of the coronary circulation will be studied during reflex and emotional behavior. The role of sympathetic coronary vasoconstriction on transmural blood flow distribution and myocardial function will be studied during restricted coronary flow. Three hypotheses concerning local metabolic control of cornary blood flow will be examined. A new dual oxygen and carbon dioxide hypothesis will be tested in a closed-chest preparation. The adenosine hypothesis will be quantitatively tested employing a sensitive assay for adenosine in experiments where coronary blood flow is regulated down as well as upwards. The importance of carbon dioxide diffusional shunting in the myocardium will be evaluated in experiments involving non steady state analysis.